1. Technical Field
The present invention relates to a sound effects generation device, a sound effects generation method, and computer program product for generating sound effects for the case in which an interaction between objects such collision or contact occurs in a three-dimensional virtual space, and in particular to a sound effects generation device, a sound effects generation method, and computer program product for generating sound effects with reality for the case in which an interaction between virtual objects occurs while keeping real-time property required in a VR system.
2. Related Art
In a three-dimensional graphics technology, a three-dimensional body is treated as an aggregate of an infinitely large number of polygons, namely an approximate mathematical model, a texture expressing material quality is mapped onto the surface thereof, and further, a light source calculation is performed to provide the texture with shadings and thickness, thereby making it possible to generate a realistic three-dimensional high-resolution image.
Further, development of computer animation for automatically generating an animation of a three-dimensional body on a computer by applying morphing or other methods is actively conducted. In recent days, according to progress in the rendering technology, the reality of the computer animation has been dramatically improved, and accordingly, the computer animation is applied to various fields utilizing virtual reality (VR) such as a computer game.
The reality of the computer animation in a drawing aspect increases, whereas room is left for enhancement of reality with respect to other aspects such as a motion or a tactile impression of the body, or sound. Further, problems in the VR system are speeding up of the process and a method of applying to the system, and in the problems an important factor is simultaneous pursuit of the real-time property and the high quality image.
The present specification particularly handles a method of artificially composing sound effects for the case in which an interaction such as a collision or a contact between objects occurs to enhance reality and presence of computer animations.
Regarding the computer-aided automatic sound generation, for example, a proposal is presented for a music synthesizer for simulating sound generation structures of various natural instruments to synthesize music waveforms (see, for example, JP-A-9-305177 (Japanese Patent No. 3044375)). In this device, a drive signal for a physical model sound source is generated using an excitation envelope signal generated by an envelope signal generation section, and an amplitude envelope is provided to the music signal using an amplitude envelope signal generated by the envelope signal generation section. Further, it is configured that a constant drive signal is input to the physical model sound source to maintain the excitation without retriggering the excitation envelope even in the case in which retriggering of the amplitude envelope is performed, thereby making it possible for a person like a beginner to easily perform sound generation/performance control, and also making it possible to realize a performance like crescendoing every note without causing any delay in sound generation. However, although this device can automatically generate sound close to that of a natural instrument, it dose not answer the question of what kind of sound should be provided to the interaction such as a collision or a contact between objects on the three-dimensional virtual space.
Still further, a proposal is presented for a three-dimensional object presentation device for feeding back sound generated when scratching or hitting a physical object in response to an interactive command input from the user via a three-dimensional viewer (see, for example, JP-A-2001-256510). However, the present device attaches sound generated when scratching or hitting an original object described as three-dimensional model data to the three-dimensional model data, and only reproduces it in accordance with an instruction of the user, but dose not generate sound corresponding to the mechanical quantity such as the degree of the impact of the collision or the counterpart of the collision. Therefore, if it is applied to a VR system, the sound lacks reality.
Further, a proposal is also presented for a body interference representation device for representing the degree of interference between a plurality of bodies with an impact noise (see, for example, JP-A-2004-252756). However, the present device has previously stored impact noise data in the case in which bodies made of the same materials, for example, collide with each other separated into cases corresponding large impact, middle impact, and small impact of the collision, respectively, and directly reproduces to output either one of the impact noise data in accordance with the degree of the impact resulted in an impact deformation analysis simulation. Therefore, although the user can auditorily recognize the degree of the interference between the bodies, it seems that sufficient reality cannot be provided because the sound lacks elaboration.
A composition method of a sound source currently adopted in a VR system basically depends on a simple method of reproducing previously sampled sound, which cannot compose sound with reality supported by the physical model.
Incidentally, in the system applying the three-dimensional virtual space, real-time processing is important. In anapplicationsuchasa computergame, the case in which a large number of objects cause interactions at the same time can be assumed, and in such a case, an excessively precise physical model makes the real-time processing difficult. In other words, a sound effect generation algorism, which is simple, but has a great advantage in creating reality, is desired.